An X-SPECT imaging system made by Gamma Medica, Inc. is requested in this Shared Instrument Grant application. X-SPECT(tm) is a dual-modality small animal imaging system that combines x-ray Computed Tomography (CT) and Single Photon Emission Computed Tomography (SPECT). Thus, X-SPECT(tm) is capable of generating co-registered anatomical (CT) and functional (SPECT) maps of intact animals under anesthesia. This instrument will allow 9 NIH- funded investigators to complete and significantly improve their studies on drug development, staging of tumor progression, and monitoring of gene delivery efficacy. Importantly, the instrument will enable the investigators to complete longitudinal studies in vivo without sacrifice of experimental animals. Consequently, investigators will study fewer animals but get much more data from each animal. The X-SPECT(tm) imaging system is capable of imaging large number of single photon emitting radioisotopes that are readily available, such as 1-125 (30 keV), TI-201 (75 keV), 1-123 (159 keV), ln-111 (171, 250 keV) and 1-131 (364 keV). The capability to image 1-125 is of particular noteworthy as 1-125 is commonly used in ex vivo molecular biology studies to label nucleic acids, antibodies, and ligands in addition to various Pharmaceuticals. New Pharmaceuticals can also be iodinated relatively easily. With X-SPECT(tm), these studies can now be performed non-invasively in vivo. In addition, the X-SPECT(tm) imaging system can perform dual isotope imaging simultaneously, such that one may look at drug delivery and efficacy simultaneously using two different tracers. The use of pinhole collimator allows the spatial resolution for SPECT imaging less than 1 mm. The x-ray CT system achieves high resolution better than 100 [unreadable]m. There is no similar instrument at the Ohio State University or other research centers in the State of Ohio. The instrument will be housed in a radioisotope certified laboratory animal facility in Wiseman Hall under the supervision of a research nuclear medicine technologist, who will work closely with the internal advisory committee. The principal investigator and the research nuclear medicine technologist have received training in the use of the A-SPECT(tm) imaging system (microSPECT component of the X-SPECT1 imaging system). Users will be trained by the principal investigator, the research nuclear medicine technologist, and laboratory animal veterinarian. The software will operate in a Window environment on a networked computer that will allow the investigators to access the data from distant sites. An hourly fee will provide funds for the annual service contract. The X-SPECT(tm) system will be integrated as a component of an Imaging Core Facility (shared resource). Thus, space and utilities for the instrument plus the salary and benefits for the research nuclear medicine technologist will be provided by the Ohio State University Comprehensive Cancer Center. [unreadable] [unreadable]